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# Physics behind force fields ?

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Hi, my name is Horia and I''m new to this forum. I have a question for anyone willing to help me. What I have to do is simulate objects regarding their masses, sizes, (i lack the english word for "q" - electric fields) in a real environment. That is, interactions between objects in a scene, space modifiers (fields), etc. It may not be physics I need, because I suppose I could find the equations in any physics book (but please feel free to post me physics too), but something like a general formula to approximate all types of forces (if I''m not asking for much - I think Einstein tried something ...). Thanks! Horia (hxa@k.ro)

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You got to do a lot o´ things. The first is to create a class for the objects. Then you need a (how to write italic in html?)OBJECTS MANAGER to test object by object if they´re colliding.

Thanks, Arthur(rockslave)

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'q' is charge, by the way.

Maybe what you're looking for is this:

Electrostatic force:

F = (K*q1*q2)/d^2

K is a constant, and should be 9x10^9, I believe. q1 and q2 are the charges of the two objects, and d is the distance between them. This should give you the force between two objects, based on their charge.

Gravity is the same way, but with mass instead of charge, and a different constant ('G', but I cant remember the value right now... might be 6.67x10^-11).

By the way.. What you're referring to, I think, is the Unified Field Theory. Einstein did try to find a theory that would apply to all forces in nature (gravity, magnetism, electrostatics, etc.) but nobody has succeeded so far. I don't know that much about it though.

I can't write any more, I gotta go to school!

Good luck!

Edited by - Qoy on July 6, 2000 2:41:14 AM

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Horia: All you need is the very simple equation

F = ma

The equation means that the net force exerted on an object is exactly equivalent to its mass times its acceleration in the current frame of reference.

The trick for force fields is simply to use the equations to determine the magnitude of the force.

There is a second type of equation that you might use instead, especially for a computer simulation: the momentum equation.

P = mv = Ft

Which means that the momentum of an object can be quantified as the product of its mass and its velocity. If you are transferring momentum, the third part comes into play: the force times the time over which it is applied is equal to the transferred momentum. This is useful because you can get an approximation to collision dynamics by multiplying the impact force of two colliding objects by the size of the time step between frames/evolution steps/whatever.

There are half a dozen articles on physics in the resources section as well, just so you know.

Hope that helps. If I might make one more suggestion: it is quite useful to have a good university level intro to physics text around for this kind of stuff.

mikey

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There''s the quantum field theory about electromagnetism, weak and strong force. And there''s Einstein''s General Relativity which is a theory about gravitation.
I heard about super string theories which should include quantum field theory and gravity, but I don''t know much about it.

If you don''t want to make your simulation very accurate, you could calculate electrostatic and gravitational forces with the formulas given by the other posters (weak and strong forces are not very important in our daily life physics).

GA

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